Nice equipment you have!
Thank you for the detailed list.
Personally, I see no need whatsoever for the DBX processor/s in your system.
Your top speakers have a switch that should be in the “FLAT” position. This means that your top speakers are going to try to reproduce frequencies that you already have handled by your subs. Unfortunately, the switch does not have a 'Low Cut" position, so it is very important for you to roll off all the frequencies in the graphic EQ of the QU for your main L/R mix below let’s say 70-80 Hz. So, at least the first five EQ faders should be all the way down, this is ideal when you are augmenting them with subwoofers. This is not as good as having a sharper cutoff like the DBX processor can provide, but it is perfectly sufficient, unless you want to carry that DBX around and make those additional patching.
For my small jobs, I use QSC K12 speakers for tops and K10 speakers for monitors, they all have the switch flipped (except drum monitor) to the “with sub” position, this relieves the top speaker from wasting it’s power on low frequencies that it can not do very well anyway, thus increasing the tops’ headroom.
Here is how I personally approach sub woofers. I am 60 years of age and come from a time when there was no such thing as subwoofers. It was imperative back in the day that any “professional” loudspeaker, Altec Lansing, JBL, Electro-Voice should be able to faithfully reproduce frequencies down to at least 50-60 Hz. Engineers that designed these speakers fully understood the fact that typically, the bigger the woofer the more “air” it could move, provided of course it was housed in a very efficient bass cabinet made for it. Once subwoofers became all the rage in live pro sound, there was now no longer the need for our “quote” HUGE Full Range speakers. We could get very good sound with much smaller speakers mounted on purpose built tri-pod speaker stands or floan in the air on a truss system, but these smaller speakers desparately relied on subwoofers below them to handle frequencies that they simply COULD NOT produce faithfully. It wasn’t too long before it became common for our subwoofers to be sent audio from a separate output on the console. This allowed the engineer to route only sounds with significant bass response to them, so, things like vocals, acoustic guitars, brass that do not have useful frequencies in the sub region would not be routed to the subs, why would we? No need to clutter up the sound in our subs with these sounds.
“Instruments only to go to the sub are assigned to the SUB Out mix and their levels are up in that mix but they are NOT assigned to (levels are down in) the LR Main mix.”
NO, in the sub mix, you turn up whatever channels that have significant bass response,
but you still want that in your main L/R mix. A bass guitar and kick drum for instance would sound terrible with just subs.
Both kick and bass guitar have full range frequency response.
“These instruments need to be PRE (LR main) fader in the SUB Out mix”
NO. all channels in the sub mix should be POST fader, so that when you raise the bass guitar in the L/R mix it is automatically raised the same amount in the subs.
“Instruments that are in both mixes (like keys and continuity music) should be POST-fader (and at unity) in the SUB out mix
Is this correct?”
THAT IS CORRECT!
“What I’m not clear about is how I set my delay fills if I go this approach?
Obviously I can just run my delays as a postfader mix from LR Main as I would if I had not split the bass out to the mono sub feed… but that is going to mean my up field speakers have no kick, say. Is this what people do?”
NO, in my opinion, your delayed speakers should have everything in them just like the mains.
We’re gettin there 